What is securing-authentication?

A guide to adding sign-in, permissions, and protection for applications and APIs. It covers standards and tools such as OAuth, single sign-on, tokens, sessions, passkeys, and role-based access.

Use it to build login and signup, secure APIs, add enterprise single sign-on, support passwordless sign-in, validate tokens, and define detailed access rules.

It helps prevent unauthorized users or programs from accessing accounts, data, and protected operations.

securing-authentication — Skill for Claude Code by ancoleman

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add ancoleman/ai-design-components --skill securing-authentication

Clone the repo

git clone --depth 1 https://github.com/ancoleman/ai-design-components

Made for: Claude Code.

Or install backend-platform-skills, the plugin that ships this one along with the rest of its 3 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/ancoleman/ai-design-components/securing-authentication/github.svg)](https://agentmods.dev/skills/ancoleman/ai-design-components/securing-authentication)

Your own site

<a href="https://agentmods.dev/skills/ancoleman/ai-design-components/securing-authentication"><img src="https://agentmods.dev/badge/skills/ancoleman/ai-design-components/securing-authentication/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/ancoleman/ai-design-components/securing-authentication"><img src="https://agentmods.dev/badge/skills/ancoleman/ai-design-components/securing-authentication.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 93 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 3,306 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00093	$0.03306
Opus 5.5	$0.00037	$0.01322
Sonnet 5.5	$0.00019	$0.00661
Haiku 4.5	$0.00009	$0.00331

Measured 2mo ago against content hash 10f1a64b2fe2, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

securing-authentication scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/generate_jwt_keys.py, scripts/validate_oauth_config.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/securing-authentication/SKILL.md · 439 lines

How it starts

The opening of the file, as written. The whole thing — 439 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Authentication & Security

Implement modern authentication, authorization, and API security across Python, Rust, Go, and TypeScript.

When to Use This Skill

Use this skill when:

Building user authentication systems (login, signup, SSO)
Implementing authorization (roles, permissions, access control)
Securing APIs (JWT validation, rate limiting)
Adding passwordless auth (Passkeys/WebAuthn)
Migrating from password-based to modern auth
Integrating enterprise SSO (SAML, OIDC)
Implementing fine-grained permissions (RBAC, ABAC, ReBAC)

OAuth 2.1 Mandatory Requirements (2025 Standard)

┌─────────────────────────────────────────────────────────────┐
│           OAuth 2.1 MANDATORY REQUIREMENTS                  │
│                   (RFC 9798 - 2025)                         │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│  ✅ REQUIRED (Breaking Changes from OAuth 2.0)             │
│  ├─ PKCE (Proof Key for Code Exchange) MANDATORY           │
│  │   └─ S256 method (SHA-256), minimum entropy 43 chars   │
│  ├─ Exact redirect URI matching                            │
│  │   └─ No wildcard matching, no substring matching       │
│  ├─ Authorization code flow ONLY for public clients       │
│  │   └─ All other flows require confidential client       │
│  └─ TLS 1.2+ required for all endpoints                   │
│                                                             │
│  ❌ REMOVED (No Longer Supported)                          │
│  ├─ Implicit grant (security vulnerabilities)             │
│  ├─ Resource Owner Password Credentials grant              │
│  │   └─ Use OAuth 2.0 Device Flow (RFC 8628) instead      │
│  └─ Bearer token in query parameters                       │
│      └─ Must use Authorization header or POST body        │
│                                                             │
└─────────────────────────────────────────────────────────────┘

Read the full file on GitHub · 439 lines

Files

What ships with it

12 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 439 lines · 93 tokens per session scan A 10f1a64b2fe2

Subscribe to this mod's changes

securing-authentication is a skill published in the GitHub repository ancoleman/ai-design-components (527 stars, last pushed 11mo ago), licensed MIT. It adds 93 tokens to every session and 3,306 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Backend and APIs Claude Code Security ai-design anthropic claude claude-skills design-system

securing-authentication next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
securing-authenticationancoleman/ai-design-components	Skill	527	11mo ago	MIT	A	93	Claude Code
form-strategyrampstackco/claude-skills	Skill	1.0k	11d ago	MIT	A	107	Claude Code
seo-apiseranking/seo-skills	Skill	199	yesterday	MIT	A	218	Claude Code
mcp-server-builderOneWave-AI/claude-skills	Skill	415	18d ago	MIT	A	79	Claude Code, Codex
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netlify-developmentMindrally/skills	Skill	297	29d ago	Apache-2.0	A	78	Claude Code
apollo-graphqlMindrally/skills	Skill	297	29d ago	Apache-2.0	A	26	Claude Code